EP2922711A2 - Farm tyre - Google Patents

Farm tyre

Info

Publication number
EP2922711A2
EP2922711A2 EP13852341.0A EP13852341A EP2922711A2 EP 2922711 A2 EP2922711 A2 EP 2922711A2 EP 13852341 A EP13852341 A EP 13852341A EP 2922711 A2 EP2922711 A2 EP 2922711A2
Authority
EP
European Patent Office
Prior art keywords
tread
tyre
farm
ply
plies
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP13852341.0A
Other languages
German (de)
French (fr)
Other versions
EP2922711B1 (en
Inventor
Paolo RIZZO
Fabrizio PERETTI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bridgestone Corp
Original Assignee
Bridgestone Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Publication of EP2922711A2 publication Critical patent/EP2922711A2/en
Application granted granted Critical
Publication of EP2922711B1 publication Critical patent/EP2922711B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/1835—Rubber strips or cushions at the belt edges
    • B60C9/185—Rubber strips or cushions at the belt edges between adjacent or radially below the belt plies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/0311—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/0007—Reinforcements made of metallic elements, e.g. cords, yarns, filaments or fibres made from metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/02—Carcasses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/28—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by the belt or breaker dimensions or curvature relative to carcass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/1835—Rubber strips or cushions at the belt edges
    • B60C2009/1842—Width or thickness of the strips or cushions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/1835—Rubber strips or cushions at the belt edges
    • B60C2009/1864—Rubber strips or cushions at the belt edges wrapped around the edges of the belt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/0311—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation
    • B60C2011/0313—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation directional type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C2200/00—Tyres specially adapted for particular applications
    • B60C2200/08—Tyres specially adapted for particular applications for agricultural vehicles

Definitions

  • the present invention relates to a farm tyre .
  • a farm tyre normally comprises a toroidal carcass comprising a number of superimposed body plies and turned up at the ends about two annular beads .
  • the carcass supports an annular tread; and between the carcass and the tread is interposed a tread belt, which comprises two superimposed tread plies comprising respective metal (typically steel) cords.
  • Two tread ply wedges are interposed between the lateral ends of the two tread plies, to act as a cushion separating the tread plies. More specifically, at the join between the two tread plies, the opposite orientation of the cords of the two tread plies creates a critical point at which, when the tyre is stressed, deformation of the tread may result in slippage between the two tread plies. By absorbing and compensating for this slippage between the two tread plies, the tread ply wedges prevent it from resulting in local detachment (i.e. separation, failure) of the tread plies.
  • Patent Application DE102005049184A1 which constitutes the most recent state of the art, describes a tyre comprising ; a carcass; a tread supported by the carcass; a tread belt interposed between the carcass and the tread and comprising an outer tread ply superimposed on an inner tread ply; and two tread ply wedges, each interposed between and locally diverging the lateral ends of the two tread plies.
  • the two ends of each tread ply are covered with respective protective caps, each made of rubber and folded into a *U' about the respective end.
  • Figure 1 shows a view in perspective of a farm tyre in accordance with the present invention
  • Figure 2 shows a front view of the Figure 1 farm tyre , ⁇
  • Figure 3 shows a cross section, with parts removed for clarity, of part of the Figure 1 farm tyre;
  • Figure 4 shows a cross section, with parts removed for clarity, of part of the carcass, tread belt, and tread of the Figure 1 farm tyre;
  • Figure 5 shows a schematic cross section of the ends of two tread plies forming the tread belt of the Figure l farm tyre;
  • Figure 6 shows a schematic cross section of a tread ply insert of the Figure 1 farm tyre before being inserted inside the tyre.
  • Number l in Figures 1 and 2 indicates as a whole a farm tyre.
  • Tyre 1 comprises a toroidal tread 2 , which extends about a central axis of rotation and comprises a tread base 3 of substantially constant thickness, and a number of lugs 4 projecting (i.e. extending radially outwards) from tread base 3 and spaced about the axis of rotation.
  • Each lug 4 curves from a centre portion of tyre 1 to a corresponding shoulder of tyre l, has a truncated-cone- shaped cross section (tapering away from tread base 3) , and has a front wall and rear wall with respect to a predetermined rolling direction of tyre 1. Because of lugs 4, the so-called ⁇ void ratio' (i.e. the ratio between the footprint area not contacting the ground, and the total footprint area) is over 50% and typically 60-70%. As shown in Figure 3, the width W2 of tread 2 is traditionally measured between the ends of the lateral arcs of tread 2.
  • tyre 1 comprises a toroidal carcass 5 defined by three superimposed body plies 6 and turned up at the ends about two annular beads 7 (shown in Figure 3) .
  • each body ply comprises a number of textile (i.e. non-metal) cords embedded in a rubber strip.
  • Carcass 5 supports tread 2; and between carcass 5 and tread 2 is interposed a tread belt 8 comprising two (and only two) superimposed tread plies 9 and 10.
  • Carcass 5 is lined with an innerliner 11, which is impermeable to air and serves to retain air inside, and maintain the inflation pressure of, tyre l.
  • Carcass 5 supports two sidewalls 12 ( Figure 3) located on the outside of carcass 5, between tread 2 and beads 7,
  • tread ply wedges are interposed between the lateral ends of tread plies 9 and 10, to act as a cushion and separate tread plies 9 and 10.
  • each tread ply wedge 13 is interposed between, to locally diverge, the lateral ends of tread plies 9 and 10.
  • the purpose of diverging the lateral ends of tread plies 9 and 10 is to form a cushion and separate tread plies 9 and 10.
  • each tread ply 3, 10 comprises a number of metal (typically steel) cords 14, which are embedded in a rubber strip 15, are arranged side by side with a given spacing, and form a given (typically 75°) slope angle with the equatorial plane of tyre 1.
  • metal typically steel
  • the width W9 ( Figure 5) of the outer tread ply 9 ranges between 60% and 80%, and is preferably 75%, of the width W2 ( Figure 3) of tread 2.
  • the width W10 ( Figure 5) of the inner tread ply 10 ranges between 80% and 95%, and is preferably 91%, of the width W2 ( Figure 3) of tread 2. It is important to note that the respective widths W9 and W10 of tread plies 9 and 10 are greater than in a similar conventional tyre. In other words, tread plies 9 and io of tyre 1 are wider than in a similar conventional tyre.
  • tread plies 9 and 10 increases rigidity at the shoulders of tyre l; reduces stress on innerliner 11, caused by lugs 4 on tread 2 penetrating carcass 5; and so, in the final analysis, increases the working life of tyre 1.
  • each protective cap 16, 17 is made of the same type of rubber as rubber strips 15 of tread plies 9 and 10, i.e. a rubber (normally containing a certain amount of cobalt) allowing good mechanical adhesion to the metal ⁇ typically steel) from which cords 14 of tread plies 9 and 10 are made.
  • each protective cap 16, 17 covers an at least 10 mm wide portion of the corresponding end, and is over 0.4 mm thick.
  • Each protective cap 16 of outer tread ply 9 is independent of the corresponding tread ply wedge 13.
  • each protective cap 16 of outer tread ply 9 is initially completely separate from the corresponding tread ply wedge 13, and is folded about the end of outer tread ply 9 independently of application of the corresponding tread ply wedge 13.
  • each protective cap 16 of outer tread ply 9 is defined by an annular strip 18, which is folded into a 'U' about the corresponding end of tread ply 9 before tread ply 9 is wound about carcass 5.
  • each tread ply wedge 13 comprises a thick central body 19 interposed between tread plies 9 and 10; an outer appendix 20, which is thinner than central body 19 and folded about one end of inner tread ply 10 to form part of corresponding protective cap 17; and an inner appendix 21, which is located on the opposite side to outer appendix 20, is thinner than central body 19, and is interposed between tread plies 9 and 10.
  • Each protective cap 17 of inner tread ply 10 is thus partly defined by outer appendix 20 of the corresponding tread ply wedge 13.
  • each tread ply wedge 13 preferably has a scalene trapezium-shaped cross section (i.e. in which the trapezium has two different oblique sides) .
  • This shape has the big advantage of following the natural profile of tread plies 9 and 10, so stress is distributed more evenly, and there is less risk of air becoming trapped inside tyre 1 as it is built.
  • central body 19 of each tread ply wedge 13 has a maximum thickness of over 1.5 mm, and outer appendix 20 and inner appendix 21 have the same constant thickness of over 0.4 mm (i.e. outer appendix 20 of each tread ply wedge 13 is the same thickness as inner appendix 21) .
  • the width W20 ( Figure 6) of outer appendix 20 of each tread ply wedge 13 is over 10 mm and is preferably 15 mm.
  • the width W21 ( Figure 6) of inner appendix 21 of each tread ply wedge 13 is over 10 mm and is preferably 20 mm.
  • Farm tyre 1 described above has numerous advantages. First and foremost, farm tyre 1 described above has a long working life because of protective caps 16 and 17. More specifically, being exposed at the ends of tread plies 9 and 10, the ends of (metal) cords 14 may eventually cause mechanical damage (i.e. by "digging' into the surrounding rubber) . This localized damage may gradually impair the performance of tyre l, even to the extent of reducing its working life. With protective caps 16 and 17, on the other hand, the parts of tyre 1 close to the ends of tread plies 9 and 10 are protected mechanically from damage by the ends of (metal) cords 14.
  • farm tyre 1 described above is cheap and easy to produce, by protective caps 16 and 17 involving no major increase in material cost, and no major complication of the manufacturing process.
  • protective caps 17 are formed extremely easily from tread ply wedges 13.
  • protective caps 16 and 17 are particularly useful in combination with tread plies 9 and 10 of respective widths W9 and W10 greater than those of a similar conventional tyre.
  • increasing widths W9 and W10 of tread plies 9 and 10 shifts the ends of tread plies 9 and 10 outwards, and so shifts the ends of (metal) cords 14 into more ⁇ fragile' areas, thus making the protective function of protective caps is and 17 even more essential.
  • a synergic effect exists between the increase in widths W9 and W10 of tread plies 9 and 10, and the presence of protective caps 16 and 17.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Abstract

A farm tyre (1) having : a carcass (5) a tread (2) supported by the carcass (5) and having a number of lugs (4); a tread belt (8) interposed between the carcass (5) and the tread (2), and having an outer tread ply O) and an inner tread ply (10), which are superimposed and each have a number of metal cords (14) embedded in a rubber strip (15); and two tread ply wedges (13), each interposed between and locally diverging the lateral ends of the two tread plies (9, 10); the two ends of each tread ply (9, 10) being covered with corresponding protective caps (16, 17), each made of rubber and folded into a 'U' about the respective

Description

FARM TYRE
TECHNICAL FIELD
The present invention relates to a farm tyre .
BACKGROUND ART
A farm tyre normally comprises a toroidal carcass comprising a number of superimposed body plies and turned up at the ends about two annular beads . The carcass supports an annular tread; and between the carcass and the tread is interposed a tread belt, which comprises two superimposed tread plies comprising respective metal (typically steel) cords. Two tread ply wedges are interposed between the lateral ends of the two tread plies, to act as a cushion separating the tread plies. More specifically, at the join between the two tread plies, the opposite orientation of the cords of the two tread plies creates a critical point at which, when the tyre is stressed, deformation of the tread may result in slippage between the two tread plies. By absorbing and compensating for this slippage between the two tread plies, the tread ply wedges prevent it from resulting in local detachment (i.e. separation, failure) of the tread plies.
Patent Application DE102005049184A1 , which constitutes the most recent state of the art, describes a tyre comprising ; a carcass; a tread supported by the carcass; a tread belt interposed between the carcass and the tread and comprising an outer tread ply superimposed on an inner tread ply; and two tread ply wedges, each interposed between and locally diverging the lateral ends of the two tread plies. In this tyre, the two ends of each tread ply are covered with respective protective caps, each made of rubber and folded into a *U' about the respective end.
DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a farm tyre with a long working life, and which in particular is cheap and easy to produce.
According to the present invention, there is provided a farm tyre as claimed in the accompanying Claims .
BRIEF DESCRIPTION OF THE DRAWINGS
A non- limiting embodiment of the present invention will be described by way of example with reference to the attached drawings, in which :
Figure 1 shows a view in perspective of a farm tyre in accordance with the present invention,-
Figure 2 shows a front view of the Figure 1 farm tyre ,·
Figure 3 shows a cross section, with parts removed for clarity, of part of the Figure 1 farm tyre;
Figure 4 shows a cross section, with parts removed for clarity, of part of the carcass, tread belt, and tread of the Figure 1 farm tyre;
Figure 5 shows a schematic cross section of the ends of two tread plies forming the tread belt of the Figure l farm tyre;
Figure 6 shows a schematic cross section of a tread ply insert of the Figure 1 farm tyre before being inserted inside the tyre.
PREFERRED EMBODIMENTS OF THE INVENTION
Number l in Figures 1 and 2 indicates as a whole a farm tyre.
Tyre 1 comprises a toroidal tread 2 , which extends about a central axis of rotation and comprises a tread base 3 of substantially constant thickness, and a number of lugs 4 projecting (i.e. extending radially outwards) from tread base 3 and spaced about the axis of rotation. Each lug 4 curves from a centre portion of tyre 1 to a corresponding shoulder of tyre l, has a truncated-cone- shaped cross section (tapering away from tread base 3) , and has a front wall and rear wall with respect to a predetermined rolling direction of tyre 1. Because of lugs 4, the so-called ^void ratio' (i.e. the ratio between the footprint area not contacting the ground, and the total footprint area) is over 50% and typically 60-70%. As shown in Figure 3, the width W2 of tread 2 is traditionally measured between the ends of the lateral arcs of tread 2.
As shown in Figure 4, tyre 1 comprises a toroidal carcass 5 defined by three superimposed body plies 6 and turned up at the ends about two annular beads 7 (shown in Figure 3) . In a preferred embodiment, each body ply comprises a number of textile (i.e. non-metal) cords embedded in a rubber strip. Carcass 5 supports tread 2; and between carcass 5 and tread 2 is interposed a tread belt 8 comprising two (and only two) superimposed tread plies 9 and 10.
Carcass 5 is lined with an innerliner 11, which is impermeable to air and serves to retain air inside, and maintain the inflation pressure of, tyre l. Carcass 5 supports two sidewalls 12 (Figure 3) located on the outside of carcass 5, between tread 2 and beads 7,
Two tread ply wedges (TPWs) are interposed between the lateral ends of tread plies 9 and 10, to act as a cushion and separate tread plies 9 and 10. In other words, each tread ply wedge 13 is interposed between, to locally diverge, the lateral ends of tread plies 9 and 10. The purpose of diverging the lateral ends of tread plies 9 and 10 is to form a cushion and separate tread plies 9 and 10.
As shown in Figure 5, each tread ply 3, 10 comprises a number of metal (typically steel) cords 14, which are embedded in a rubber strip 15, are arranged side by side with a given spacing, and form a given (typically 75°) slope angle with the equatorial plane of tyre 1.
in a preferred embodiment, the width W9 (Figure 5) of the outer tread ply 9 ranges between 60% and 80%, and is preferably 75%, of the width W2 (Figure 3) of tread 2. In a preferred embodiment, the width W10 (Figure 5) of the inner tread ply 10 ranges between 80% and 95%, and is preferably 91%, of the width W2 (Figure 3) of tread 2. It is important to note that the respective widths W9 and W10 of tread plies 9 and 10 are greater than in a similar conventional tyre. In other words, tread plies 9 and io of tyre 1 are wider than in a similar conventional tyre. This increase in the width of tread plies 9 and 10 increases rigidity at the shoulders of tyre l; reduces stress on innerliner 11, caused by lugs 4 on tread 2 penetrating carcass 5; and so, in the final analysis, increases the working life of tyre 1.
As shown in Figure 5, the two ends of each tread ply 9, 10 are covered with respective protective caps 16/ 17, each made of rubber and folded into a Λϋ' about the respective end. In a preferred embodiment, each protective cap 16, 17 is made of the same type of rubber as rubber strips 15 of tread plies 9 and 10, i.e. a rubber (normally containing a certain amount of cobalt) allowing good mechanical adhesion to the metal {typically steel) from which cords 14 of tread plies 9 and 10 are made. In a preferred embodiment, each protective cap 16, 17 covers an at least 10 mm wide portion of the corresponding end, and is over 0.4 mm thick.
Each protective cap 16 of outer tread ply 9 is independent of the corresponding tread ply wedge 13. In other words, each protective cap 16 of outer tread ply 9 is initially completely separate from the corresponding tread ply wedge 13, and is folded about the end of outer tread ply 9 independently of application of the corresponding tread ply wedge 13. More specifically, each protective cap 16 of outer tread ply 9 is defined by an annular strip 18, which is folded into a 'U' about the corresponding end of tread ply 9 before tread ply 9 is wound about carcass 5.
As shown in Figure 5, each tread ply wedge 13 comprises a thick central body 19 interposed between tread plies 9 and 10; an outer appendix 20, which is thinner than central body 19 and folded about one end of inner tread ply 10 to form part of corresponding protective cap 17; and an inner appendix 21, which is located on the opposite side to outer appendix 20, is thinner than central body 19, and is interposed between tread plies 9 and 10. Each protective cap 17 of inner tread ply 10 is thus partly defined by outer appendix 20 of the corresponding tread ply wedge 13.
The central body 19 of each tread ply wedge 13 preferably has a scalene trapezium-shaped cross section (i.e. in which the trapezium has two different oblique sides) . This shape has the big advantage of following the natural profile of tread plies 9 and 10, so stress is distributed more evenly, and there is less risk of air becoming trapped inside tyre 1 as it is built.
In a preferred embodiment, central body 19 of each tread ply wedge 13 has a maximum thickness of over 1.5 mm, and outer appendix 20 and inner appendix 21 have the same constant thickness of over 0.4 mm (i.e. outer appendix 20 of each tread ply wedge 13 is the same thickness as inner appendix 21) . In a preferred embodiment, the width W20 (Figure 6) of outer appendix 20 of each tread ply wedge 13 is over 10 mm and is preferably 15 mm. In a preferred embodiment, the width W21 (Figure 6) of inner appendix 21 of each tread ply wedge 13 is over 10 mm and is preferably 20 mm.
Farm tyre 1 described above has numerous advantages. First and foremost, farm tyre 1 described above has a long working life because of protective caps 16 and 17. More specifically, being exposed at the ends of tread plies 9 and 10, the ends of (metal) cords 14 may eventually cause mechanical damage (i.e. by "digging' into the surrounding rubber) . This localized damage may gradually impair the performance of tyre l, even to the extent of reducing its working life. With protective caps 16 and 17, on the other hand, the parts of tyre 1 close to the ends of tread plies 9 and 10 are protected mechanically from damage by the ends of (metal) cords 14.
Furthermore, farm tyre 1 described above is cheap and easy to produce, by protective caps 16 and 17 involving no major increase in material cost, and no major complication of the manufacturing process. In this connection, it is important to note how protective caps 17 are formed extremely easily from tread ply wedges 13.
It is important to note how protective caps 16 and 17 are particularly useful in combination with tread plies 9 and 10 of respective widths W9 and W10 greater than those of a similar conventional tyre. In other words, increasing widths W9 and W10 of tread plies 9 and 10 shifts the ends of tread plies 9 and 10 outwards, and so shifts the ends of (metal) cords 14 into more ^fragile' areas, thus making the protective function of protective caps is and 17 even more essential. In other words, a synergic effect exists between the increase in widths W9 and W10 of tread plies 9 and 10, and the presence of protective caps 16 and 17.

Claims

1) A farm tyre (1) comprising:
a carcass (5) comprising at least two superimposed body plies (6) ;
a tread (2) supported by the carcass (5) and having a number of lugs (4) projecting from a tread base (3) ;
a tread belt (8) interposed between the carcass (5) and the tread (2) , and comprising an outer tread ply (9) and an inner tread ply (10) , which are superimposed and each comprise a number of metal cords (14) embedded in a rubber strip (15) ; and
two tread ply wedges (13) , each interposed between and locally diverging the lateral ends of the two tread plies (9, 10);
wherein the two ends of each tread ply (9, 10) are covered with corresponding protective caps (IS, 17), each made of rubber and folded into a about the respective end;
the tyre (1) being characterized in that each protective cap (17) of the inner tread ply (10) is partly defined by an outer appendix (20) of the corresponding tread ply wedge (13) .
2) A farm tyre (1) as claimed in claim 1, wherein each protective cap (IS, 17) is made of the same type of rubber as the rubber strips (15) of the tread plies (9, 10) . 3) A farm tyre (1) as claimed in Claim 1 or 2 , wherein each protective cap (16, 17) is made of rubber capable of adhering mechanically to the cords (14) ) of the tread plies (9, 10).
4) A farm tyre (1) as claimed in Claim 1, 2 or 3, wherein each protective cap (16) of the outer tread ply (9) is independent of the corresponding tread ply wedge (13) .
5) A farm tyre (1) as claimed in one of Claims 1 to 4, wherein each protective cap (IS, 17) covers an at least 10 mm wide portion of the corresponding end.
6) A farm tyre (1) as claimed in one of Claims 1 to 5, wherein each protective cap (16, 17) is over 0.4 mm thick.
7) A farm tyre (1) as claimed in one of Claims 1 to 6, wherein each tread ply wedge (13) comprises ;
a thick central body (19) interposed between the two tread plies (9, 10) ,- an outer appendix (20) , which is thinner than the central body (19) and folded about one end of the inner tread ply (10) to form part of the corresponding protective cap (17) ; and
an inner appendix (21) , which is located on the opposite side to the outer appendix (20) , is thinner than the central body (19) , and is interposed between the two tread plies (9, 10) .
8) A farm tyre (1) as claimed in Claim 7, wherein the outer appendix (20) of each tread ply wedge (13) is the same thickness as the inner appendix (21) .
9) A farm tyre (l) as claimed in Claim 7 or 8, wherein the central body (19) of each tread ply wedge (13) has a scalene trapezium-shaped cross section.
10) A farm tyre (1) as claimed in Claim 7, 8 or 9, wherein the central body (19) of each tread ply wedge (13) has a maximum thickness of over 1.5 mm.
11) A farm tyre (1) as claimed in one of Claims i to
10, wherein the width (W20) of the outer appendix (20) of each tread ply wedge (13) is over io mm, and is preferably
15 mm.
12) A farm tyre (1) as claimed in one of Claims 1 to
11, wherein the outer appendix (20) of each tread ply wedge (13) is over 0.4 mm thick.
13) A farm tyre (1) as claimed in one of Claims 1 to
12, wherein the width (W9) of the outer tread ply (9) ranges between 60% and 80% of the width (W2) of the tread (2) , and preferably equals 75% of the width of the tread (2) .
14) A farm tyre (1) as claimed in one of claims 1 to 13, wherein the width (W10) of the inner tread ply (10) ranges between 80% and 95% of the width (W2) of the tread (2) , and preferably equals 91% of the width of the tread (2) .
EP13852341.0A 2012-11-21 2013-11-21 Farm tyre Active EP2922711B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000584A ITRM20120584A1 (en) 2012-11-21 2012-11-21 TIRE FOR AGRICULTURAL USE
PCT/IB2013/060315 WO2014080362A2 (en) 2012-11-21 2013-11-21 Farm tyre

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EP2922711A2 true EP2922711A2 (en) 2015-09-30
EP2922711B1 EP2922711B1 (en) 2017-02-08

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CN (1) CN104812593B (en)
BR (1) BR112015011643B1 (en)
IT (1) ITRM20120584A1 (en)
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WO (1) WO2014080362A2 (en)

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FR3159767B1 (en) * 2024-02-29 2026-01-23 Michelin & Cie tire tread for agricultural vehicle
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BR112015011643A2 (en) 2017-07-11
CN104812593A (en) 2015-07-29
CN104812593B (en) 2018-02-23
US9950569B2 (en) 2018-04-24
WO2014080362A2 (en) 2014-05-30
WO2014080362A3 (en) 2014-07-24
US20150314649A1 (en) 2015-11-05
ITRM20120584A1 (en) 2014-05-22
EP2922711B1 (en) 2017-02-08
WO2014080362A8 (en) 2014-12-24
BR112015011643B1 (en) 2020-11-17
RU2640293C2 (en) 2017-12-27
RU2015123997A (en) 2017-01-10

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